1. Field
Aspects of the present invention relate generally to a rechargeable battery.
2. Description of the Related Art
A rechargeable battery has the characteristic that it may be recharged after discharge, differing from a primary battery that is incapable of being recharged. Small-capacity rechargeable batteries are used for small portable electronic devices such as mobile phones, notebook computers, camcorders, etc., while large-capacity rechargeable batteries are used as a motor-driving power source for larger devices, such as hybrid vehicles or large-capacity power storage devices.
Presently, high powered rechargeable batteries using a non-aqueous electrolyte with high energy density have been developed and formed into a large capacity rechargeable battery by coupling a plurality of rechargeable batteries in series for use in driving a motor of a device, for example, a motor of an electric vehicle requiring high electrical power. These rechargeable batteries can be cylindrical or angular in shape.
Rechargeable batteries generally include an electrode assembly installed inside a case and to/from which a current may be charged or discharged. An electrode terminal is electrically connected to the electrode assembly often via a current collector. The electrode terminal generally includes a positive terminal and a negative terminal, and is coupled and fixed to a cap plate for closing and sealing an opening of the case of the rechargeable battery. The electrode terminal used for this rechargeable battery can be one of a rivet-type electrode terminal or a bolt-type electrode terminal. To fix a rivet-type electrode terminal to the cap plate, the rivet-type electrode terminal must first be fixed to the cap plate, and then one side of the rivet-type electrode terminal contacting the cap plate must be rivet-processed and welded, making the combination process of fixing the electrode terminal complicated.
For rechargeable batteries, structures configured with different materials have been shown to have excellent properties, similar to a combination degree of structures combined through friction welding compared to laser welding. In contrast, it has been shown that combining structures formed with the same material through laser welding is more efficient than the same combination through friction welding.
When the rivet-type electrode terminal and the cap plate are formed with different materials, they are generally rivet-processed, and because friction welding is not easy to perform on a part having different materials coupled to the cap plate, it may be necessary to perform laser welding on the rivet-processed part. Therefore, in these rechargeable batteries, a structure made of the same material as the cap plate is coupled to one side of the rivet-type electrode terminal coupled to the cap plate through friction welding, and the structure is rivet-processed and then laser welded on the rivet-processed part. As a result, when the rivet-type electrode terminal and the cap plate are formed with different materials, the process for fixing the electrode terminal to the cap plate becomes complicated.